1. Field of the Invention
The present invention relates to a method of making cathodes for electric current-producing cells, and more particularly to making such cathodes by in situ thermal decomposition of cathodes derived from ammonium metal-chalcogen compounds.
2. Description of the Prior Art
There has been considerable interest in recent years in developing high energy density batteries for voltaic cells. Exemplary of the developing systems is a high energy density electrochemical cell utilizing intercalation compounds of the transition metal chalcogenides as cathode-active materials and using alkali metal anodes, as set forth in U.S. Pat. No. 4,009,052. U.S. Pat. No. 3,915,740 describes a cell having lithium anode-active material and MoS.sub.x (where 2.ltoreq.x.ltoreq.3) as its cathode-active material, and U.S. Pat. No. 3,864,167 describes some fibrous transition metal trichalcogenides as cathode-active materials. Cell data for VS.sub.2 and V.sub.x Fe.sub.1-x S.sub.2 (x.gtoreq.0.5) cathodes showing less than or about one lithium per unit cathode material reversible capacity has recently been reported by Murphy et al (Materials Research Bulletin, Vol. 12, p. 825 et seq. (1977) and by DiSalvo et al (Bull. Am. Phys. Soc., Vol. 23, p. 244 et seq. (1978)). Also, the mineral patronite, VS.sub.4, has been investigated and found to have a capacity for less than one lithium and found to be irreversible by Murphy and Trumbore (Journal Crystal Growth, Vol. 39, p. 196 (1977)). U.S. Pat. No. 3,655,585 describes a method of making cathodes of cathode-active material vanadium pentoxide by the thermal decomposition of ammonium vanadate in an apparently oxidizing environment.
Recently, D. W. Murphy et al (J. Electrochem Soc. Vol. 126 p. 497 (March, 1979)) described the preparation of V.sub.6 O.sub.13 (VO.sub.2.167) by reaction of V.sub.2 O.sub.5 and V at 650.degree. C. and alternatively by thermal decomposition of NH.sub.4 VO.sub.3 in an inert atmosphere below 450.degree. C. However, the present invention is believed to antedate this disclosure as evidenced by many of the examples and the disclosure of the parent application hereof.
U.S. Pat. No. 4,144,384, Jacobson et al, describes some specific embodiments of the present invention but has issued to the same inventive entity as in the present application. Further, the present invention antedates U.S. Pat. No. 4,144,384, which discloses but does not claim the present invention.